Process for treatment and extraction of organic cork compounds by a dense fluid under pressure

ABSTRACT

Process for the treatment of cork or a cork-based material particularly with a view towards extracting contaminating organic compounds, in which said cork or said cork-based material is put into contact with a dense fluid under pressure at a temperature of from 10 to 120° C. and at a pressure of from 10 to 600 bars. Manufacturing installation for parts made of cork or a cork-based material, such as bottle corks, comprising an installation for treatment or extraction by putting the said cork or the said material into contact with a dense fluid under pressure.

BACKGROUND OF THE INVENTION

This application is a Continuation application of U.S. application Ser.No. 10/089,162, now U.S. Pat. No. 7,192,490, which is a 371 ofPCT/FR00/02653 filed on Sep. 26, 2000.

FIELD OF THE INVENTION

This invention relates to a process for the treatment and extraction oforganic cork compounds using a dense fluid under pressure, andparticularly a super-critical fluid.

DESCRIPTION OF THE RELATED ART

Cork is a natural impermeable and lightweight material derived from thebark of some types of oak such as cork oak, most of which are found incountries bordering the Mediterranean, in Europe and in North Africa.

Cork is used particularly for making bottle corks used to closereceptacles such as bottles containing liquids for food consumption,particularly wine.

Bottle corks have been used to close wine bottles for very many years.

About 15 billion bottles are closed in this manner throughout the worldevery year.

Cork is a natural product that has properties particularly well suitedfor conserving wine in bottles. Cork is elastic, resilient,compressible, has a high coefficient of friction, is impermeable toliquids, and has a sufficient permeability to gases to enable theexchanges necessary for the product to mature in bottles.

However, occasionally, some alterations to the smell and/or taste of theconserved liquid such as wine compromise the coherence of the naturalpair consisting of the cork and the wine.

These alterations are all referred to under the generic term “corkyflavour”.

It has been shown that most of these alterations are completelyindependent of the cork (stopper) and originate in the wine itself or inits preparation and storage.

However, other alterations are caused by the cork (stopper) and a greatdeal of work has been done throughout the world to find the cause of theproblem and to find a solution.

Thus, it has been found that cork tastes can be globally distributedinto “genuine” corky flavours, corky flavours, and finally musty tastes.

A “genuine” corky flavour is a putrid taste making the wine undrinkable.This defect is related to yellow stain, in other words growth of ahigher fungus, Armillaria mellea.

Cork boards affected by yellow stain are usually put aside during thefirst cork board selection sort.

The frequency of this defect is of the order of 1 in 10 000 to 1 in 100000.

The corky flavour is due to the fact that cork is not inert towardswine. It provides aromatic compounds in variable proportions that caninteract positively or negatively with the wine.

The presence of more or less accentuated undesirable tastes is relatedto preparation of cork, particularly the storage duration in the yardand boiling conditions.

The frequency at which these tastes occur can be minimised by respectingthe Code International des Pratiques Bouchonnières (InternationalCork-cutter Practices Code).

A “corky flavour” and a “musty taste” are very often confused. Mustytastes are fungus, forest undergrowth and mould type tastes related tothe presence of organic molecules, the most frequently mentioned beingmethyl-isoborneol and its derivatives with a “musty and camphrous”smell, geosmine with an “earthy” smell, methylthio-ethyl-pyrazine with a“musty and sulphurous” smell, alcohols and unsaturated cetones in C₈with a “mushroomy” smell, and particularly chloroanisoles and especially2,3,4,6-TeCA2,4,6-TCA (trichloroanisole) and 2,3,4,6-TeCA(tetrachloroanisole).

These chloroanisoles, which smell very strongly and for which theperception threshold in water is between 0.03 and 4 ng/l, originate frommethylation of slightly volatile chlorophenols that have a very mildsmell. This reaction is carried out by a very large number of moulds andis equivalent to a chlorophenol detoxification reaction.

Chlorophenol type precursors may originate from different locations andfrom health care products, insecticide treatments, atmospheric pollutionand cork degradation reactions, for example subsequent to some washingoperations by hypochlorite.

Finally, particularly to eliminate “corky flavours” as much as possible,cork is subjected to various treatments and particularly cleaningoperations.

Cleaning treatments and operations take place at different stages in theproduction or maintenance of cork objects, for example such as bottlecorks (stoppers).

A treatment consists of eliminating micro-organisms from the cork,responsible for the production of undesirable metabolites during thetreatments themselves after finishing.

Thus, before the bottle corks are finished, they are washed withchlorine using lime chloride or hypochlorite followed by washing withoxalic acid using a traditional process, or washing with peroxide(hydrogen peroxide or peracetic acid), or using sulfamic acid, or theyare washed with metabisulfite using a solution of SO₂.

After the bottle corks have been finished (washed or unwashed), they aretreated by the injection of SO₂, by ethylene oxide or by gammaradiation.

The most frequently used process for eliminating volatile compoundsresponsible for tastes is the use of hot or boiling water, known as“boiling”.

Thus, in the F. BORDAS process that was first used in 1904, the partsare placed in a chamber heated to 120° C. for 10 minutes and a vacuum isthen created, and then the pressure is restored by allowing steam topenetrate.

The chamber is then heated to 130° C. for 10 minutes.

This old method has never been supported by any precise and evaluateddata.

The CHAMPCORK process consists of putting parts in a chamber saturatedwith steam at 130° C. and a pressure of 180 kPa for 18-20 minutes.Atmospheric pressure is then restored.

All these techniques described above have many disadvantages, including:

-   -   low efficiency towards organic compounds causing undesirable        tastes;    -   incomplete efficiency towards some micro-organisms.

Furthermore, most of the techniques mentioned use chemical products thatintroduce risks, nuisances and constraints, both for the personnel whoare using them and for the environment.

Thus, operators are exposed to the risk of inhaling noxious substances,which makes it necessary to wear a mask, whereas the effluents generatedby these treatments contain large quantities of compounds containingsulphur and/or chlorine and must be subjected to a long and expensivepurification process before they can be rejected.

The document by MIRANDA, Ana M. et al, “High-pressure extraction of corkwith CO₂ and 1.4 dioxane”, Process. Technol. Proc. (1996), 12 (HighPressure Chemical Engineering), pages 417-422, discloses a process forthe treatment of cork using high pressure mixes (170 bars) of CO₂ anddioxane within a temperature range from 160° C. to 180° C. Suberine isextracted in this manner.

The conditions of the process disclosed in this document are completelyincompatible with use of cork after treatment; particularly for themanufacture of bottle corks.

Document U.S. Pat. No. 5,364,475 discloses a wood cleaning process,particularly a process for extraction of pentachlorophenol (PCP) typecompounds or other non ionic biocide organic compounds in which the woodis firstly cut into suitable size pieces, and is then subjected to atreatment by a fluid in the super-critical state, for example CO₂.

A modifying agent or co-solvent chosen among methanol, ethanol andacetone is preferably added to the super-critical fluid in a proportionof 1 to 10% by weight, which increases the extraction efficiency.

The process according to this document is only applicable topentachlorophenol (trichloroanisole and tetrachloroanisole are excluded)and can only extract contents compatible with potential changes to someenvironmentalist standards (Toxicity Characteristic Leaching ProfileLevel) (of the order of 0.1 ppm).

The outer shell of treated trunks is mentioned in this patent althoughit does not mention if the outer shell consists of cork or bark, sincethe outer shell described in this patent could also include wood if theimpregnation process caused strong penetration into the PCP material.There is a very precise definition of the word “cork” in French and inEnglish, to mean a type of material and also a variety. Cork oak(Quercus suber L.¹) is a very particular species not mentioned in theAmerican patent referred to above.

Furthermore, this patent states that the treated product must be dividedinto particles with a thickness not exceeding 1 to 5 mm but table 7demonstrates that the extraction efficiency drops very quickly above athickness of 0.25 mm.

This grinding and shredding step is extremely penalising and it meansthat the process cannot be used to treat cork boards or bottle corksunder any circumstances.

Similarly, document DE-A-4 223 029 discloses a process for extraction oftar oil from old wood or wood waste, in which the wood is firstly groundto a size of 10 to 40 mm, and then is put into contact with asuper-critical extraction fluid such as CO₂ or an aliphatic hydrocarbonwith 3 to 5 carbon atoms for a sufficiently long time to reduce theconcentration of tar oil to a required threshold.

A co-solvent such as ethanol or isopropanol can be added to thesuper-critical fluid with a content of 2 to 5% by volume of the moisturecontent in the wood.

Document WO-A-98/16288 applies to a process and an installation for theextraction of inorganic and/or possibly organic polluting compounds by asuper critical fluid such as CO₂, starting from a material such as wood.

The extracted polluting organic compounds are particularlypolychlorobiphenyls, chlorophenols and polychlorophenols (PCP), lindane,polyaromatic organic compounds, insecticides, fungicides, and otheradditives that might be found in the wood.

A co-solvent such as water may be added to the super-critical fluid inproportions of 5 to 20% by weight.

None of the processes described above using a dense fluid under pressureis applied to cork, but cork is an extremely specific material for whichthe properties are very different from the properties of wood, mainly interms of elasticity and density.

It could be added that the chemical composition of cork is verydifferent from the chemical composition of wood, particularly concerningthe composition in suberine, lignin and cellulose.

The chemical composition of cork is usually as follows:

46% suberine (the main constituent of cork). The very highcompressibility and elasticity of cork are due to the presence of largequantities of suberine.

25% lignin (structure of the cellular walls).

12% cellulose and other polysaccharides. Cork cellulose is in free form.

6% tannins.

6% ceroids. Ceroids repel water and contribute to the impermeability ofcork.

5% ash and other compounds.

Refer to the following documents for further information on thissubject:

A. Guillemonat. Progrès récents dans l'étude de la constitution chimiquedu liège (Recent progress in the study of the chemical composition ofcork). Ann. Fac. Sc. De Marseille, 1960, 30, 43-54.

H. Pereira. Chemical composition and variability of cork from Quercussuber L. wood Sci. Technol., 1988, 22 (3), 211-218.

The chemical composition of dry wood is usually as follows, forcomparison purposes:

60% cellulose.

25% lignin (structure of cellular walls).

15% other compounds.

Cork is a specific material and is fundamentally different from wood dueto this difference in its composition.

The study of prior art described above shows that there is a need thathas not been satisfied for a process for the treatment or cleaning ofcork in order to eliminate contaminating and polluting organic compoundssuch as chlorophenols and chloroanisoles responsible particularly forundesirable tastes and smells.

There is still a need for a process for cleaning cork in order toselectively eliminate the said contaminating organic products withoutalso affecting some other organic compounds such as suberine, ceroids,lignin and cellulose that confer desirable or even essential propertiesto the cork, particularly in view of its use for the manufacture ofbottle corks.

Preferably, this process must also simultaneously eliminate or limit thepresence and proliferation of micro-organisms such as bacteria and fungiin cork.

BRIEF SUMMARY OF THE INVENTION

The purpose of this invention is to provide a cork treatment processthat satisfies a number of requirements including all the needs andrequirements mentioned above.

Another purpose of this invention is to provide a process for thetreatment of cork that does not have the defects, disadvantages,limitations and disadvantages of processes according to prior art andthat solves problems with processes according to prior art.

This purpose and other purposes are achieved according to the inventionby a process for the treatment of cork or a cork-based material in whichthe cork or the said cork-based material is put into contact with adense fluid under pressure at a temperature of from 10 to 120° C. and ata pressure of from 10 to 600 bars.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an apparatus that may be used to carry outthe invention;

FIG. 2 shows a graph comparing the cleaning efficiency of various corks;

FIG. 3 shows the mechanical characteristics of corks under differentcleaning conditions;

FIG. 4 shows the effect of a co-solvent on the reduction of microbialgrowth.

DETAILED DESCRIPTION OF THE INVENTION

“Cork” refers to materials made exclusively of cork, while cork-basedmaterial treated by the process according to the invention refers tomaterials usually containing a high proportion of cork, compositecork-based materials, etc.

As we will see later, cork or the cork-based material may be shaped orunshaped.

Under the temperature and pressure conditions of the process accordingto the invention, cork or the cork-based material can be cleaned and/ordecontaminated with an excellent efficiency.

In other words, with the process according to the invention, it ispossible to extract and/or eliminate all or almost all contaminants,pollutants and undesirable or organic compounds located in cork or thecork-based material, without affecting the content of compoundsnaturally present in cork or the cork-based material such as ceroids,suberine, lignin and cellulose, or keeping them at an acceptable level.

These compounds and their contents confer the necessary and essentialproperties to cork for most of its applications, and particularly forthe manufacture of bottle corks.

Therefore, the properties of cork related to these compounds and theircontents, are not deteriorated by the treatment in the process accordingto the invention.

In particular, these properties are physical, chemical and organoleptic.

The process according to the invention can be used to obtain cork or acork-based material for which the properties after treatment areexcellent, and are equivalent to or better than the properties of corkor the cork-based material treated by processes according to prior art,without any of their disadvantages.

Thus, and as already mentioned above, due to the drastic temperature andpressure conditions involved, the process disclosed in the document byMIRANDA et al. causes a considerable deterioration of the properties ofcork, such that they become completely incompatible with use of corkafter this treatment for the manufacture of bottle corks. Furthermore,the purpose of this document is findamentally different, since unlikethe process according to the invention, the objective is to extractsuberine from cork, and not to keep the suberine in cork in order topreserve its properties.

Similarly, the process disclosed in this document is not intended toextract or specifically eliminate undesirable organic compounds, whichis the essential purpose of this invention.

According to the invention, use of the fluid in the dense state underpressure under the conditions defined above can advantageously replaceand/or improve conventional cork cleaning and/or decontaminationprocesses.

According to the invention, the fluid in the dense state under pressureis preferably put into contact with cork or the cork-based material at apressure of 100 to 300 bars and at a temperature of 40 to 80° C.

Also preferably, the said dense fluid under pressure is a fluid in thesupercritical state, in other words the dense fluid is at a pressure andunder a temperature such that the fluid is in the super-critical state.

Thus, in the process according to the invention, a gaseous compound forexample is used under normal temperature and pressure conditions, andits density is increased by increasing its pressure. The temperature canalso be modified to enter the range in which the fluid is in the densestate and under pressure, preferably in its super-critical state. Thoseskilled in the art will find it easy to define this range.

According to the invention, the extractive properties of the fluid canbe varied in a controlled manner by varying the pressure and thetemperature parameters while remaining within the dense range underpressure, and preferably within the super-critical range for the fluidconcerned; thus, increasing the pressure and temperature increases thesolubilisation capacity, whereas reducing the pressure reduces theviscosity and increases the diffusivity.

Thus, according to the invention, during the treatment it is possible tocarry out compression/decompression cycles, preferably very fast cyclesfor example with an amplitude of the pressure variation from 10 to 100bars and time intervals varying from ten seconds to a few minutes, forexample 10 minutes, the complete process continuing for example forbetween 1 and several hours, for example 10 hours.

This increases the penetration of the solvent fluid into the material,which has the result of improving the cleaning performances and theinternal flexibility of the cork.

The advantages of the process according to the invention are essentiallyrelated to the specific characteristics of fluids in the dense stateunder pressure, and particularly in the super-critical state, and due tothe fact that, surprisingly, this technique can be applied to cork.

Considering the considerable differences between the properties of woodand cork, it was absolutely unpredictable that a process similar to theprocess for treating wood could also be applicable to cork or tocork-based materials.

The difference in composition between wood and cork that was clearlydemonstrated above means that cork is an extremely specific material andthat application of a dense fluid under pressure to treat cork could notbe deduced from use of the same fluid to treat wood. Furthermore, theprocess according to the invention is applicable to cork originatingfrom a very particular variety of tree (Quercus suber L.) that is raisedseveral times so that its bark produces a material with properties thatare very different from the bark of wood from other varieties. Theresulting applications cover a wide variety of domains.

The fluid used may for example be chosen among carbon dioxide; sulphurhexafluoride; nitrous oxide; nitrogen monoxide; light alkanes, forexample with one to five carbon atoms such as methane, ethane, propane,butane, isobutane, pentane; alkenes such as ethylene and propylene; andsome organic liquids such as methanol and ethanol; etc.

Obviously, any compound that can be in a dense state under pressure, andparticularly in a super-critical state, can be used, if use-of thiscompound is compatible with cork or cork-based materials.

Carbon dioxide is preferred since it has the advantage that it isrelatively easy to use; it is inexpensive, non-toxic, non-inflammableand has easily obtainable critical conditions (critical pressure Pc=7.3MPa and critical temperature Tc=31.1° C.).

CO₂ in the dense state under pressure, a liquid or super-critical,solubilises most organic compounds with molar masses less than or equalto 2000 g/mole. Therefore it is an excellent solvent for organiccompounds called “undesirable compounds”, for example such aspentachlorophenol (PCP) and tri or tetra-chloroanisoles (TCA and TeCA)originating from the natural content in cork and/or accidentalcontamination.

The relative chemical inertia of CO₂ in the dense state makes itparticularly suitable for use in a process designed to clean cork or acork-based material, particularly when this cork or this material isintended to be used to make parts for food applications such as bottlecorks.

Furthermore, the low viscosity of CO₂ in the dense state, its highdiffusion coefficients and its very low interface tension enablecleaning of cork parts with complex shapes and complex physicalcharacteristics, particularly in the presence of adsorption phenomena,either on the surface of the part or internally.

The advantages of CO₂ also include the fact that it can be used as acomplement to or as a replacement for conventionally used processes:

-   -   an almost perfect extraction efficiency for undesirable organic        compounds, due to specific physicochemical characteristics;    -   an almost zero residual effluent volume, limited strictly to        recuperation of extracted pollutants (including PCP and TCA) and        recycling of purified CO₂ gas;    -   a large saving, for example in terms of solvent due to the lack        of treatment or recuperation of effluents, or due to the use of        inexpensive CO₂;    -   respect of the environment, since the process generates no or        very few aqueous effluents;    -   modularity of the dissolving capacity of the molecule that        varies as a function of usage conditions, in other words the        pressure and the temperature, in order to adapt to the nature of        the products to be extracted and/or the required application.

In other words, the pressure and temperature characteristics can be usedto control a fluid for which the dissolving capacity can be varied interms of solubilisation, and particularly contaminating, polluting andundesirable compounds of cork, and the extraction dynamics particularlywithin the porous solid matrix from which the cork is formed.

The excellent volatility of CO₂ under normal conditions (temperature andpressure) characterises it as a dry solvent not requiring any dryingstep after cleaning. Furthermore, CO₂ does not leave any residual traceon the treated part.

Treatment in a CO₂ atmosphere can avoid risks of oxidation and improvethe final surface condition of the part.

Preferably, according to the invention, a “co-solvent” compound is addedto the dense fluid under pressure. The addition of this type ofco-solvent to a dense fluid under pressure within the specific contextof treatment of cork, is not described or even suggested in prior art.

Surprisingly, according to the invention, it was observed that theaddition of a co-solvent to the dense fluid under pressure can result intotal extraction of contaminating and polluting organic compounds, inother words undesirable compounds, from cork or a cork-based material.

As mentioned above, the addition of the co-solvent guarantees selectiveextraction of undesirable organic compounds, while maintainingacceptable levels of the content of compounds naturally present in thecork such as ceroids, suberine, lignin and cellulose.

In other words, the addition of an appropriate co-solvent is a means ofcontrolling the selectivity towards the extraction of pollutants,contaminants and undesirable organic compounds that are to be eliminatedand extracted.

Furthermore, and completely surprisingly, it has been observed that theaddition of a co-solvent causes a reduction in the growth ofmicro-organisms very much greater than the reduction obtained with CO₂alone, due to a type of synergy effect, and this reduction in the growthof micro-organisms can change from a factor of 100 to a factor of 1million when the co-solvent is added.

According to the invention, the said co-solvent is chosen for examplefrom among water, aqueous solutions, alcohols, for example aliphaticalcohols from 1 to 5 C. such as ethanol, methanol, butanol, ketones suchas acetone, and their mixtures.

Among aqueous solutions, it is worth mentioning buffer solutions forexample such as phosphate and/or hydrogenosphosphate solutions, etc., tostabilise the pH of the process; antibiotic solutions such as penicillinand/or fungicide solutions, to increase the elimination ofmicro-organisms; anti-oxidant solutions such as ascorbic acid tostabilise the material, etc.

According to the invention, the said co-solvent is added to the densefluid under pressure with a content of 0.01 to 10% by weight, andpreferably 0.02 to 1% by weight and even more preferably 0.02 to 0.1% byweight.

If the co-solvent is water, part of it may already be present in cork,and only the necessary quantity to give the concentrations mentionedabove will be added to the super-critical fluid.

Thus, the invention also relates to a process for selective extractionof contaminating organic compounds from cork or a cork-based material,in which the said cork-based material is treated by bringing it intocontact with a dense fluid under pressure under the temperature andpressure conditions according to the invention, a co-solvent being addedto the dense fluid under pressure.

The contaminating or polluting organic compounds mentioned above, towhich the process according to the invention can be applied, are organiccompounds that could be located in cork and that form pollutants orcontaminants that must be eliminated to enable use of cork or thecork-based material without any disadvantages.

Other organo-chlorinated compounds such as lindane and polyaromaticorganic compounds (HPA) may also be extracted using the processaccording to the invention.

The process according to the invention is also applicable to theextraction of organic compounds such as triazole, synthetic pyrethroids,insecticides and fungicides that may be present in cork.

Note that for simplification reasons, the term “organic compounds” isfrequently used in the plural in the description, although it is obviousthat the process according to the invention may apply to a singleorganic compound.

According to the invention, the said extracted contaminating, pollutingorganic compounds are essentially and preferably the organic compoundsresponsible for undesirable tastes and/or smells.

An “undesirable” taste or smell usually means a taste or a smell that isnot required in cork, particularly under the conditions under which itis used, for example when coming into contact with a consumable liquid.

An “undesirable” taste or smell can generally be defined as a taste orsmell considered to be “unpleasant” by most users.

These compounds responsible for undesirable tastes and/or smells areusually (poly)chlorophenols and other phenolic compounds and(poly)chloroanisoles and other derivatives of anisole, and particularlypentachlorophenol (PCP), trichloroanisole (TCA) and tetrachloroanisole(TeCA).

The compounds mentioned above are present in cork either naturally or inan induced manner.

Extraction according to the process described in our patent is done onorganic products that do not originate from a treatment carried outintentionally as is the case for cut wood (trunks, boards, etc.) forpreservation of boards or other wood-based materials that need to bedepolluted for recycling purposes.

As already mentioned above, surprisingly the extraction processaccording to the invention can be used for complete and selectiveelimination of organic compounds responsible for undesirable tastesand/or smells in cork, while keeping the content of a number ofcompounds such as ceroids, suberine, tannins, lignin and celluloseconferring physical, chemical and organoleptic and mechanical qualitiesessential to cork, particularly when it is used for the production ofbottle corks, at a suitable level.

The elimination of undesirable organic compounds and particularly TCA,without simultaneously eliminating ceroids necessary particularly forthe good mechanical behaviour of a bottle cork, is a surprising effectof the process according to the invention and is not described orsuggested by prior art.

The process thus satisfies a need that has not been satisfied for a longtime in the state of the art and overcomes a widespread preconceptionamong professionals in the cork business by which it is impossible toselectively eliminate undesirable compounds without affecting beneficialcompounds.

Within the context of the extraction process according to the invention,the fluid used is preferably CO₂ and the co-solvent, chosen from amongwater and aqueous solutions is added to the CO₂ under pressure with acontent of 0.01% to 10% by weight. According to the invention, aselective extraction of pollutants and contaminants can be achievedtogether with a reduction (by synergy) of the growth of micro-organismsat contents of the co-solvent as low as 0.01% by weight, for example0.02 to 1% by weight, and preferably 0.02 to 0.2% by weight.

The temperature and pressure ranges involved during the extraction ortreatment operation can vary, provided that the fluid always remains adense fluid under pressure, preferably in a super-critical state, andthat compression/decompression cycles can also be carried out, asmentioned above.

The temperature and pressure ranges depend particularly on the nature ofthe fluid used.

These temperature and pressure ranges have already been mentioned aboveand are particularly applicable to CO₂.

These conditions can be maintained throughout the duration of theprocess, or simply at the beginning of the extraction or treatmentprocess, in which these conditions correspond to a high density and ahigh temperature—the overriding phenomenon being solubilisation—in orderto very quickly extract compounds outside the matrix.

In general, the treatment or extraction time (in other words the timeduring which cork or the cork-based material is left in contact with thedense fluid under pressure) is between one or a few minutes, for example10 minutes, or one or a few hours, for example 10 hours, depending onthe fluid flow and the quantity of materials to be treated.

After a few minutes, in other words for example after 5 to 20 minutes,and when the pressure and temperature conditions according to theprocess are applied to the materials, the extraction takes place veryquickly due to a very high diffusion capacity.

After reaching equilibrium, for example after 30 to 60 minutes, it canbe considered that extraction is complete with an efficiency for exampleclose to 99.9%.

Extraction efficiencies are always very high, even for compoundscontaining chlorine, for which the efficiency is better than 85%, forexample 98%.

The solvent content used, in other words the weight of the densefluid—solvent—preferably super-critical, used compared with the weightof cork or the cork-based material, is usually 10 to 100 kg of fluid/kgof cork or cork-based material. Advantageously, the process according tothe invention comprises a fluid recycling step after the extraction ortreatment and after one or several physicochemical separation steps, inorder to separate the fluid from the extracts.

Conventionally, the first separation steps consist of reducing thedensity of the fluid by a series of pressure reductions and temperatureincreases in order to get closer to the gaseous state.

The dissolving capacity of the fluid drops, and thus some of theextracts solubilised in the extraction step are recovered.

Thus, the process according to the invention for the extraction ortreatment of cork can be used to physically separate the useable cork orthe cork-based material usually representing about 90 to 99% of theinitial product, from undesirable, natural or artificial organicproducts representing less than about 1% to 10% of the initial productand that can be manipulated, treated and eliminated specifically andtherefore can be easily controlled, while the gas or fluid mayadvantageously be recycled so that it can be used for another extractionor another treatment.

Consequently, the treatment or extraction process may be done in aclosed circuit or in a loop which means that advantageously, due to aninitial and constant content of a fluid such as CO₂, the undesirableorganic compounds can be gradually depleted from the or the cork-basedmaterial.

More precisely and after the extraction process itself, the processaccording to the invention advantageously comprises one or severalsteps, for example up to three physicochemical separation steps in whichthe density of the fluid is reduced, for example by a series of pressurereductions and temperature increases, preferably between 1 and 3, inorder to get closer to the gaseous state.

For example, the conditions in these successive steps may be 90 bars and50° C., 70 bars and 40° C., 50 bars and 40° C.

Since the isolating capacity of the fluid is reduced, the extractspreviously solubilised in the extraction step are thus recovered.

These extracts are in the form of more or less fluid concentratedliquids and may be treated specifically and possibly destroyed in thecase of pollutants.

The gas obtained at the end of the separation step is preferablyrecycled to the extraction step, where it is reconditioned in order torestore temperature and pressure conditions so that it is in asuper-critical state, the gas can thus be firstly cooled to atmosphericpressure, stored in liquid form and then heated and compressed beforebeing sent to the extraction process itself.

Before being recycled, the gas is preferably purified, for example byactive carbon, in order to eliminate traces of volatile organic productsthat were not separated in the previous step.

Thorough purification of the gas is usually necessary, otherwiseextraction performances will be very much reduced.

According to the invention, cork or the cork-based material may also besubjected to a mechanical and/or chemical treatment, before thetreatment or extraction using the dense fluid under pressure.

A mechanical and/or chemical treatment usually means a known treatmentas described above within the context of the presentation of prior art.

This treatment is preferably a treatment using hot or boiling water,usually called a “boiling” treatment.

According to the invention, cork or the cork-based material is shapedbefore or after the said treatment or the said extraction using thedense fluid under pressure; either earlier than the said mechanicaland/or chemical treatment, if any, preceding the said treatment or thesaid extraction by the dense fluid under pressure; or later than thesaid mechanical and/or chemical treatment, if any, after the saidtreatment or the said extraction by the dense fluid under pressure.

In other words, in the process according to the invention, the part orparts to be cleaned, in other words the unprocessed parts before orafter stamping and before or after the mechanical and/or chemicaltreatment, and preferably the boiling treatment, are put into contactwith the fluid in the dense state under pressure.

This shaping, working or stamping is intended to bring cork or thecork-based material, usually pure cork, into the shape required for theplanned use, which may be boards, stamped or moulded bottle corks, forexample bottle corks made of composite materials, cork parts used forthe manufacture of objects or devices made for food or non-foodapplications.

We saw above that the process according to the invention is particularlysuitable for preparing cork or a cork-based material with optimumqualities for manufacturing a bottle cork.

Thus, the invention also applies to a process for manufacturing bottlecorks made of cork or made of a cork-based material that includes atleast one treatment or extraction step as described above.

The invention also relates to an installation for manufacturing partssuch as bottle corks made of cork or made of a cork-based material, thatincludes an installation for the treatment or extraction of the saidmaterial by bringing it into contact with a dense fluid under pressure,under the conditions described above

This step may be included at any point in the process for manufacturingbottle corks.

“Substantially free from” means that the content of these compounds issuch that the undesirable smell and/or taste caused by the compoundsis/are not present in cork or the cork-based material according to theinvention.

Bottle corks according to the invention are particularly useful forclosing off receptacles such as bottles, barrels, drums or otherreceptacles containing food products and preferably liquids such as wineproducts.

Finally, the invention relates to a process for disinfection of cork orcork-based material and/or making it aseptic by bringing the saidmaterial into contact with a dense fluid under pressure, to which aco-solvent is added.

The invention will be better understood after reading the followingdescription with reference to the attached drawings, in which:

-   -   FIG. 1 diagrammatically shows a sectional view of an elevation        of an example installation for an embodiment of the process        according to the invention;    -   FIG. 2 is a graph showing the cleaning efficiency E as a        percentage of cork parts with PCP and TCA supplements, boiled        (at right) and unboiled (at left) for different treatment times        t (in hours) and different densities of CO₂ (in g/l), the        columns with close cross-hatching being applicable to PCP        (pentachlorophenol) and columns with wide cross-hatching being        applicable to TCA (2,4,6-trichloroanisole);    -   FIG. 3 contains a graph showing the evaluation of the mechanical        strength of “tubed” bottle corks cut from cork boards treated        and not treated by CO₂, and boiled and unboiled control parts;

The mechanical strength was evaluated by measuring compression pressures(PC) and return pressures (Pret).

-   -   FIG. 4 is a graph showing the logarithmic variation, variation        (log), of microbial growth as a function of the applied        temperature (T (° C.)) during the treatment by CO₂ only (curve        in dashed lines) or by CO₂ plus water (curve with solid lines).

FIG. 1 diagrammatically shows a sectional view of an elevation of theinstallation according to the invention.

Obviously, a figure of this type only shows an example embodiment of aninstallation and is only given for illustrative purposes and are in noway restrictive.

This figure shows means of bringing the cork or cork-based material intocontact in the form of an extractor or autoclave (1).

This type of extractor can resist the pressure applied in the processaccording to the invention and it is also provided with heating andtemperature regulation means in the form of a thermostat controlleddouble shell (2), inside which a suitable heat transporting fluid (3),(4) can circulate.

The volume of the extractor or autoclave is variable, and dependsparticularly on the quantity of cork to be processed; it can easily bedetermined by those skilled in the art.

The cork or cork-based material parts to be treated (5), for example inthe form of boards, sheets or bottle corks, are put into the extractor,and these parts are preferably placed on one or several supports orgrills.

FIG. 1 shows only one extractor (1) in the installation, but it is quiteobvious that the installation may comprise several extractors (forexample 2 to 10 laid out for example in series).

The installation also comprises means of bringing a fluid, such as CO₂to the dense state under pressure, for example to the super-criticalstate.

Thus in FIG. 1, the fluid, for example CO₂, from a recycling pipe (6)and/or possibly a storage and make up reservoir, for example CO₂ (7)penetrates through a valve (8) into a liquefaction reservoir (9)provided with temperature regulation means in the form of a thermostatcontrolled double shell (10), inside which a suitable heat transportingfluid (11, 12) can circulate.

The said fluid such as CO₂ is thus liquefied and circulates through aflowmeter (13), and is then pumped and compressed by a pump (14), forexample a membrane type or piston type compression pump, or for exampleby a compressor to the extractor (1).

Before being introduced into the extractor (1) through a valve (15), thefluid, for example pumped CO₂, is heated in an exchanger (16) called a“super critical” exchanger in which it is heated until it is underconditions in which it is in the form of a dense fluid under pressure,and in particular a dense super-critical fluid.

In other words, the fluid is heated above its critical temperature inthis exchanger, which for example is 31.1° C. for CO₂.

FIG. 1 also shows means of injecting a co-solvent in the form of a highpressure pump (17) supplied by a co-solvent reservoir (18) thatprogressively adds a known quantity of co-solvent in the compressedfluid through a pipe (19) connected to the fluid supply pipe to theextractor (1), on the input side of the exchanger (16) and on the outputside of the compression pump (14).

Therefore, the temperature of the mix consisting of the compressed fluidand the co-solvent is increased to the working temperature through theexchanger (16).

According to the invention, the fluid and co-solvent mix impregnates theparts to be treated (5) made of cork or cork-based material, for examplecork boards or bottle corks already stamped, in the chamber of theextractor (1), and extracts the undesirable contaminating chemicalcompounds.

One or several parts may be treated simultaneously, depending on thesize of the parts to be treated.

The impurities contained in the fluid such as CO₂ will increase as afunction of the contact time between the two bodies, provided that thesolubility is not too great, by splashing.

Thus, the super-critical fluid at the inlet to the extraction autoclave(1) will be a homogeneous fluid solution such as CO₂ and co-solvent.

The cork content could also be mixed with a known proportion ofco-solvent before the extraction operation, in other words before thefluid is added into the autoclave.

The current of fluid such as CO₂, in which compounds extracted from thecork are solubilised, is then sent to separation means connected to thetop of the extractor or the autoclave (1), and for example comprisingthree cyclone type separators (20, 21, 22) connected in series, each ofthem being preceded by an automatic pressure reduction valve (23, 24,25).

Three cyclone type separators (20, 21, 22) are shown in FIG. 1, but itis obvious that the number, type and sequence of the separators canvary.

The pressure reduction applied to the fluid takes place at constanttemperature.

The organic compounds in liquid form extracted from cork are separatedor demixed from a gas, for example CO₂, in each separator.

Compounds extracted from cork are drawn off (26, 27, 28), for example atthe bottom of the separators, and are recovered and then otherseparation, extraction or purification operations, for examplecentrifuging, settlement or liquid/liquid extraction are possiblycarried out on them, or they may be destroyed.

The gas derived from the separation, such as CO₂, is cleaned and is thensent to fluid recycling means that comprise essentially a pipe (6) and a“cold” exchanger (26) or liquefier, for example in the form of athermostat controlled chamber, to be sent to the low temperature liquidreserve (9) kept cool by a cooling batch that cools and liquefies thefluid (11, 12) such as CO₂.

The cleaning means (29) have been shown in FIG. 1 as a reflux column oran active carbon column (29) placed on the fluid recycling means.

Finally, the installation comprises regulation means (not shown),particularly for the pressure, in the different parts of the process,that comprise a regulation system composed of pressure sensors,regulators and pneumatically controlled needle valves.

The invention will now be described with reference to the followingexamples that are given for illustrative purposes and are in no wayrestrictive.

EXAMPLES

Cork samples were treated or cleaned using the process according to theinvention, using an installation similar to that shown in FIG. 1, thefluid being dense CO₂ under pressure.

More precisely, this installation comprises:

-   -   a CO₂ reserve in the form of a sphere containing about 300 kg,        this type of sphere being commercially available;    -   a liquefier in the form of a steel chamber occupying about 2        litres and with a low temperature thermostat control, by means        of a cooling bath;    -   a 0 to 300 bar compression pump with a maximum flow of 10 kg/h;    -   a 0 to 300 bar co-solvent pump to gradually add a co-solvent        such as water at about 0.01 to 0.1% by weight, into the dense        CO₂ under pressure;    -   a super-critical exchanger in the form of a thermostat        controlled double shell;    -   an extractor in the form of an autoclave with a volume of 6        litres and a maximum pressure of 300 bars provided with a double        shell;    -   three cyclone type separators provided with automatic pressure        reduction valves.

The cork parts to be treated are placed in the autoclave and are in theform of boards or sheets with dimensions equal to a few tens ofcentimetres.

The cork parts to be treated are divided into two different batches:

-   -   a first batch of cork parts was boiled in accordance with        normally accepted practice for this type of material; namely        immersion for 1 h 30 in water at 100° C.;    -   a second batch of cork parts was unboiled.

The two batches were subjected to a supplementation treatment with anaqueous solution of PCP (pentachlorophenol) and TCA (trichloroanisole)by dipping in a receptacle for several hours, namely from 1 to 5 hours,with ultrasound action to complete impregnation of cork parts.

The content of PCP and TCA in the cork parts is measured before andafter treatment of these parts by the process according to theinvention.

These measurements are made by grinding the sample, liquid-solidextraction, transformation into acetate for the PCP, purification oncartridge and analyses by gaseous phase chromatography and massspectrometry.

Mechanical tests are also carried out on bottle corks “tubed” fromtreated and untreated, boiled and unboiled cork parts (boards). Thesetests are as follows:

-   -   measurement of the compression pressure (PC) that consists of        measuring the pressure to be applied to reduce the nominal        diameter of a 24 mm bottle cork down to 16 mm, which is the        compression diameter of a bottle-corking machine;    -   measurement of the return pressure (Pret) that is the        measurement of the pressure exerted by the bottle cork while it        returns from 16 mm, which is the compression diameter of a        bottle-corking machine, to 21 mm, which is the maximum diameter        of a bottle neck.

Finally, microbial flora culture tests for yeast, moulds, mesophilicaerobic germs, enterobacteria, coliforms, bacillus and sulfito-reducinganaerobia, were carried out by counting on specific seeding media andevaluated by the reduction in the logarithm of the growth of this floraafter treatment by CO₂ in the dense state under pressure, with andwithout water as co-solvent.

Examples 1 and 2 given below are particularly related to the eliminationof organic compounds from cork samples that had previously beensupplemented to make their contents very much greater than contentsnormally encountered in cork production intended for manufacturingbottle corks.

Example 1

Parts (boards) made of cork representing a total quantity of about 400 gof cork were treated using the process according to the invention.

No prior boiling treatment was done on these parts.

The initial content of PCP and TCA after an analysis using the operatingmethod defined above, was found to be 75 ppb for each contaminatingproduct.

The operating conditions of the process according to the invention aregenerally as follows:

-   -   co-solvent: distilled water at about 0.2°/₀₀;    -   operating pressures: from 100 to 300 bars;    -   temperature: about 50° C.;    -   treatment time: from 1 to 5 hours;

At the end of this treatment, these cork parts are analysed to determinethe residual content of PCP and TCA.

The mechanical strength of the bottle corks “tubed” from these boards isalso measured by making measurements of the compression pressure “PC”and the return pressure “Pret” described above.

For the final evaluation, the measurements were also made on controlbottle corks tubed in parts (boards) not treated using the processaccording to the invention in order to compare the mechanical strengthobtained after treatment using the process according to the invention,with the strength obtained in the absence of any treatment using thisprocess.

FIG. 2 shows the results obtained in terms of cleaning efficiency as apercentage, which is defined as the ratio of the contaminant masses (PCPor TCA), measured by analysis in parts before and after cleaning usingthe process according to the invention, and using the following formula:

${{Efficiency}\mspace{11mu}\%} = ( {1 - {\frac{{contaminant}\mspace{14mu}{mass}\mspace{14mu}{after}\mspace{14mu}{treatment}}{{contaminant}\mspace{14mu}{mass}\mspace{14mu}{before}\mspace{14mu}{treatment}} \times 100}} $

The cleaning efficiency is shown in FIG. 2 for different treatmentdurations and for each contaminant PCP and TCA.

FIG. 3 shows the results obtained for evaluation of the mechanicalstrength (in N/cm²) of bottle corks tubed from treated and untreatedcork parts (boards), using measurements of the compression pressure “PC”and the return pressure “Pret”.

A control sample that was not treated using the process according to theinvention is used as a reference.

Refer to table 1 for information about the results of tests on themechanical strength of bottle corks tubed from treated and untreatedcork boards using the process according to the invention.

The table also shows specific conditions for the treatment according tothe invention used in this example.

Example 2

The process according to the invention was used to treat cork parts(boards), with a total quantity of about 400 g of product.

Unlike example 1, these parts were previously subjected to a boilingtreatment (immersion for 1 h 30 in water at almost 100° C.).

The initial content of PCP and TCA determined by analysis using theoperating method described above, was found to be 50 ppb for eachcontaminating product.

The same measurements described in example 1 were made on the cork parts(boards).

These measurements were also made on bottle corks made from the controlpart not treated by the process according to the invention.

As in example 1, the results for the cleaning efficiency are shown inFIG. 2; whereas the results for the mechanical strength of bottle corkstubed from the parts (boards) are shown in FIG. 3 and are also given intable 1.

TABLE 1 PC (N/cm²) Pret (N/cm²) Boiled Board (B) 120 bars, 60° C., TestP1 Control B 26 1.8 1 h, 6.5 kg/h BP1 28 1.8 250 bars, 60° C., Test P2Control B 26 1.8 5 h, 10 kg/h BP2 30 1.8 Unboiled Board (AVB) 120 bars,60° C., Test P1 Control AVB 29 1.6 1 h, 6.5 kg/h AVBP1 26 1.7 250 bars,60° C., Test P2 Control AVB 29 1.6 5 h, 10 kg/h AVBP2 27 1.9 *PC:compression pressure Pret: return pressure

An analysis of the results given in examples 1 and 2 for the cleaningefficiency (FIG. 2), shows that the efficiency obtained after treatmentaccording to the invention using dense CO₂ under pressure is very closeto 100%, both for extraction of PCP for which the efficiency varies from84 to 100%, and for extraction of TCA which is 100% in all cases.

In example 1 for unboiled samples, the efficiency ranges from 84 to 92%for extraction of PCP, which gives a residual content of 12 to 6 ppb foran initial content of 75 ppb.

The efficiency obtained for the extraction of TCA is complete and equalto 100%, which means that the residual content of TCA is less than thedetection limit of the analysis method used.

In example 2, the PCP extraction efficiency for the boiled samples isfound to be slightly better and ranges from 94 to 100%, corresponding toa residual content varying from 3 ppb to a value below the detectionlimit of the PCP and TCA analysis method, for treatment conditionsidentical to those in example 1, but with a 50 ppb lower initial contentof PCP and TCA.

The extraction efficiency on TCA is complete and equal to 100%.

For the results obtained for the mechanical strength of the bottle corkstubed from the treated cork parts (boards) (FIG. 3), all results inexamples 1 and 2 show the excellent mechanical strength of cork partstreated by CO₂ using the process according to the invention.

A difference in the measurements of the compression pressure PC, isobserved between bottle corks tubed from the control parts not treatedwith CO₂ compared with bottle corks that are tubed in the parts cleanedby CO₂, but this difference does not exceed 5 N/cm².

Furthermore, the variation affecting the mechanical strength is of thesame order of magnitude for bottle corks tubed from treated parts as isnormally obtained on bottle corks tubed from the control parts, asdemonstrated by the following values of the mechanical strength:

-   -   bottle corks tubed from control parts not treated with CO₂;    -   27.5±1.7 N/cm² (for n=4);    -   bottle corks tubed from parts treated with CO₂ (examples 1 and        2);    -   27.8±1.7 N/cm² (for n=4);

Similarly, no significant variation was found in the results obtainedwhen measuring return pressures Pret, for which values obtained are:

-   -   1.7±0.1 N/cm² (n=4) for control parts;    -   1.8±0.1 N/cm² (n=4) for treated parts (examples 1 and 2).

Finally, it is observed that the density of CO₂ is a parameter that hasless influence than the treatment time or the initial content of organiccompounds responsible for the undesirable taste (PCP and TCA).

The results given above show that cork parts treated by the processaccording to the invention can also be used for stamping and/or for winebottle corks.

Example 3

This example shows the anti-microbial efficiency of the processaccording to the invention when water, is added as a solvent to thedense fluid under pressure.

Parts of a substrate similar to the described material (cork) are thustreated by dense CO₂ under pressure, to which 0.02% by weight of waterhas been added, at a pressure of 300 bars and under a temperaturevarying from 0 to 60° C.

The growth of micro-organisms is determined using the operating methoddescribed above.

Equivalent substrate (cork) parts are treated under the same conditions,but without any water being added to the dense fluid under pressure, andthe growth of micro-organisms is determined once again.

The results obtained are shown in FIG. 4 that indicates the logarithmicvariation of microbial growth obtained as a function of the temperature(in ° C.) applied during the treatment.

The curve shown in solid lines is the curve for treatment by CO₂ towhich water has been added, while the curve shown in dashed lines isapplicable to treatment by CO₂ alone without the addition of water.

It is found that the treatment applied using dense CO₂ under pressureresults in a maximum reduction in microbial growth by a factor of 100,and only for a treatment temperature of 60° C.

On the other hand, this reduction is as high as a factor of 1 millionfor a temperature of 40° C. when CO₂ is used with water.

Without being restricted to any particular theory, it is probable thateven small proportions of water in the presence of CO₂ produce carbonicacid such that the pH of the mix becomes acid.

The combined action of pressure and acidity thus produces an effect thatis highly damaging to the survival of the micro-organisms present.

1. A process, comprising: extracting one or more organic compounds fromat least one of cork or a cork-based material with a dense fluid underpressure at a temperature of from 10 to 120° C. and a pressure of from10 to 600 bar; wherein the dense fluid under pressure comprises at leastone cosolvent selected from the group consisting of water and an aqueoussolution, in an amount of from 0.01 to 10% by weight based on the totalweight of the dense fluid under pressure, and wherein the dense fluid isin a supercritical state.
 2. The process according to claim 1, furthercomprising: adding the cosolvent to the dense fluid under pressure,before the extracting.
 3. The process according to claim 1, wherein theextracting is carried out at a temperature of from 31.1 to 80° C. and apressure of 73 to 300 bar.
 4. The process according to claim 1, whereinthe dense fluid under pressure is at least one selected from the groupconsisting of carbon dioxide, sulfur hexafluoride, nitrous oxide,nitrogen monoxide, an alkane containing 1 to 5 atoms of carbon, analkene, and an organic liquid.
 5. The process according to claim 1,wherein the cosolvent is water and the dense fluid under pressure issupercritical carbon dioxide.
 6. The process according to claim 1,wherein the one or more organic compounds is selected from the groupconsisting of a (poly)chlorophenol, a (poly)chloroanisole, and the oneor more organic compounds are extracted without simultaneouslyeliminating any ceroids.
 7. The process as claimed in claim 1, whereinthe one or more organic compounds is selected from the group consistingof a pentachlorophenol, trichloroanisole and a tetrachloroanisole, andthe one or more organic compounds are extracted without eliminating anyceroids.
 8. The process as claimed in claim 1, wherein the cosolvent isat least one aqueous solution selected from the group consisting abuffer solution of phosphate, a buffer solution of hydrogen phosphate, asolution of ascorbic acid and a mixture of water and an alcohol.
 9. Theprocess according to claim 1, wherein the extracting is carried out forfrom 30 to 60 minutes and at least 85% by weight of one or morepolychlorophenols present in the cork or the cork-based material isextracted.
 10. The process as claimed in claim 1, wherein the extractingis carried out for from 30 to 60 minutes and at least 98% by weight ofone or more polychloroanisoles present in the cork or the cork-basedproduct is extracted.
 11. The process according to claim 1, wherein from10 to 100 kg of the dense fluid under pressure is extracted with 1 kg ofthe cork or the cork-based material.
 12. The process as claimed in claim1, wherein the cosolvent is present in an amount effective to reducemicrobial growth on the cork or the cork-based material more than thereduction in the amount of microbial growth when the cork or thecork-based material is extracted with the dense fluid under pressure inthe absence of the cosolvent.
 13. The process according to claim 1,wherein the extracting includes alternately increasing and decreasingthe pressure in a plurality of cycles with an amplitude of pressurevariation of from 10 to 100 bar and a time interval of from 10 secondsto 10 minutes.
 14. The process according to claim 1, wherein thecosolvent is water.
 15. The process as claimed in claim 1, wherein theextracting is carried out to remove organic compounds having anundesirable taste, an undesirable smell, or both an undesirable tasteand an undesirable smell.
 16. The process according to claim 1, whereinthe one or more organic compounds are selected from the group consistingof a phenolic compound and an anisole compound.
 17. The processaccording to claim 1, further comprising: gasifying the dense fluidunder pressure by changing at least one of the temperature and thepressure to separate one or more extracts, and recycling the gasifieddense fluid.
 18. The process according to claim 1, further comprising:chemically or mechanically treating the cork or the cork-based materialbefore or after extracting the one or more organic compounds from thecork or the cork-based material with the dense fluid under pressure. 19.The process according to claim 1, further comprising: shaping the corkor the cork-based material before or after the extracting.
 20. A processfor manufacturing bottle corks, comprising: shaping a bottle cork fromthe cork or the cork-based material obtained by the process of claim 1.21. The process according to claim 1, wherein the dense fluid underpressure is supercritical CO₂, the cosolvent is water, the temperatureis from 40 to 80°C., and the pressure is from 100 to 300 bar.
 22. Theprocess according to claim 1, further comprising: forming one or moreextracts by extracting the cork of the cork-based material with thedense fluid under pressure, separating the dense fluid under pressurefrom the extracts, vaporizing at least a portion of the separated densefluid under pressure to form a gaseous fluid, and recycling the gaseousfluid.
 23. The process of claim 1, wherein the dense fluid underpressure is supercritical CO₂, the cosolvent is water and the extractingremoves trichloroanisole from cork or the cork-based material.
 24. Theprocess according to claim 5, wherein the dense fluid under pressurecomprises the cosolvent in an amount of from 0.02 to 1% by weight. 25.The process according to claim 5, wherein the dense fluid under pressurecomprises the cosolvent in an amount of from 0.02 to 0.1% by weight. 26.The process according to claim 14, wherein the cosolvent furthercomprises at least one selected from the group consisting of afungicide, an antibiotic and an antioxidant.
 27. The process accordingto claim 19, wherein the shaping includes shaping the cork or thecork-based material into the form of one or more of a bottle cork, aboard and a sheet.
 28. The process according to claim 21, wherein thedense fluid under pressure comprises the cosolvent in an amount of from0.02 to 0.2% by weight.